When Did This Rift Break Up? Sampling and Dating Continental Rupture
The Gulf of California rift records the processes of rift initiation, evolution to continental breakup and formation of passive margins. Wrenching of Baja California away from mainland México obliquely opened the Gulf of California seaway ~8-6 million years ago. Geologic mapping and geochronology of rift-related rocks, such as these undeformed, basin capping, 4.3 Ma Tuffs of Hipat Mesa on Isla Tiburón, is crucial to understanding the timing and degree of crustal thinning related to plate boundary deformation. Field-based observations of rift initiation dynamics are essential for evaluating the mechanisms that lead to rift localization and the transition to oceanic spreading. Photograph taken Spring 2010. Looking east at the southern edge of Hipat Mesa, southern Isla Tiburón, México (28.8478, -112.4724). Photo credit: Scott Bennett (USGS)